Improved apparatus for



I UNITED STATES PATENT OFFICE.

11. BoLrHoFF,-oF BURLINGTON, lOWA.

Specification forming part or Letters Patent No. 46.632, dated March 7,1865.

roan whom it may concern;

2- Be itknown that'I, H. BOLTHOFF, of Burlington, in the county of Des Moines and State of Iowa, have invented a' new and Improved Mill for Grinding Quartza'nd Am'algamati'n g Precious Metals Oontained'Therein and I do the hereby declare that the following is a full, clear, and exact description thereof, which will enable others skilledin the artto make and use the same, reference being had to 'the accompanying drawings, forming part of this's'peci fication, in nihieh-= Figure 1 is a vertical central section of my invention taken in the line mm, Fig. 2; Fig.

2, a plan or top view of the same, partly in section; Fig.3, an inverted plan or face'view of a portion of the lower, mullerjljFi'g. 4, an inverted plan or face view ofia-Fpor'tion of the upper muller; 'Fig. 5, a section of a portion of thelower mullertaken in the line 3 y, Fig. 2; Fig. 6, a section of a portion of the upper mul v ler taken iuthe line a z Fig. 2 Fig. 7, a horizontal section of Fig. 1 taken in the line as w. Fig. 8, a horizontal section of Fig. 1 taken in the line p 3 Fig. 9, a vertical section of a portion"of the pan taken in ,the line 2 2, Fig.2. f

. Similar letters of reference indicate like parts.

- This invention relates to a new and improved mill for grinding quartz and amalgamatingthe precious metals contained therein;

. and itconsists in using within a pan two rotary mullers arranged in such a manner that theylwill rotatein reverse directions, said mullersbeing provided with openings and placed one over the other, as hereinafter fully shown and described,.whereby the pulp will be thoroughly ground and the mercury intermixed therewith,'so that all the particles of precious metals containedin the former will be brought in contact with'the mercury and amalgamated, the work being rapidly performed and in very efficient manner. 1 f

I A represents a framing, which maybe constructed in any proper manner, to support the pan B, which may be of the usual or any proper form and of any suitable or desired dimensions. This pan is east or formed with a central hollow conical hub, 0, through which a hollow shaft, D, passes, and within this hollow shaft l) there is fitted a spindle, E, the

lower end of which is stepped in a bridge-tree,

F, in the framin'gA.

On the lower part of the spindle E, below I the shaft D, there is keyeda bevel-wheel, G,

and on the lower \part of the shaft D there is keyed a similar wheel, H, and intothese wheels G H bevel-.pinions I I gear, thelatter being on a horizontal shaft, J, to which the driving.

- ower is applied. .By this arrangement the ollo-w shaft D and spindle E are made to rofate-in reverse directions, and the re'lative'size of. the gearing G H I I isi'such-that the shaft and spindle will have an q fil speed;

On the upper part of the hollow shaft D there is formed a square, a, which is above the conical hub G of the pan, and on orover this square there is fitted the square por tion of aconical hub, J, which extends down over the hub U of the pan and is "connected to or east with the lower muller,

K. (See Figs. 1 and 8.) This 'muller K is rather less in diameter than the pan B, and

it is provided at its iinder or face side with shoes L, of V shane, (see Fig. '3,') and fitted Yin. groovesin the under side of K,and secured to it by rivets or bolts 11. These shoes Lare designed to be fitted loosely to muller K,so that they will have a certain degree of vertical play and conform to the inequalities ofthe bottom of the pan should it not be perfectly level or in thesame plane.

The muller K, between the shoes L,is pro vided with openings 0, which are of V form'in their trans\ erse section, as shown in Fig.6.

.The spindle E, above the'hollow shaft D, is

reduced in diameter to receive a sleeve, B1,!

This sleev j' externally is of square formthe greater porwhich is fitted loosely upon it.

tion of its length, there being a cylindrical projection or flange, d, at its lowerenld, over which a flange, d, at theupper'enid of the hub J of muller K, fits, as shown clearly in Fig. 1.

The. sleeve M is provided with an oblique slot or opening, e, at two opposite sides of it,

and a pin, f, passes horizontallythrough the" reduced parts ofthe spindle E and the slots 01' openings 0. This pin f and openings .2 cause the spindle F. to rotate the-"sleeve M, while the oblong openings 0 admit of the sleeve M being raised and lowered on the spindle, said movement or adjustment of the sleeve being *efiected by means of a screw, N, "which works in aninternal thread in the upper end of the sleeve'M and rests or bears upon the upper end of the spindle E.

, U'represents a muller which is directly over the muller K, and is provided at its under or face side with shoes P, which are arranged and applied similar to the shoes L of the muller K. The muller 0, between the shoes P, is provided with openings 9, (see more particularl y Figs at and 6,) and said muller has a central concentric hub, Q, which is hollow or of annular form and flaring at its upper end, and has bow-shaped arms R attached to it, at the center of which there is asquare opening, h,

to fit over or upon the sleeve M. The muller '0 is of the same diameter as the muller K. I

The pan B is provided with two outlets, 'i "5, through which the contents of the pan are drawn ofit. Y

a The operation is as follows: The shaft J is rotated by any convenient power, and the two mullers K O rotate-in opposite or reverse directions. The pulp is fed into the hollow hub Q and passes between the two mullers O K, where it is ground, owing to the revolution of the mullers, the pulp passing through the openings 0 in the muller K and underneath the shoes L thereof, whence it is subjected to a further grinding between saidshoes L and the bJttom of the pan. The pan is supplied with comes thoroughly intermixed with the pulp d \ring the grinding processr The foreign light portions of the pulp are forced up around the edges of the mullers O K, the amalgamatedportions remaining below, and the light portion passes through the openings g of muller O, and is again subjected to a further grinding action between the two mullers. JIhe reverse movements of the two muliers render the grinding process very eflicient and cause the 'work to be rapidly performed.-

' The mullers may be raised at any time, so

that the lower muller will be above or free from the, bottom of the pan, by turning the 'screw N, the upper muller, of course, rising with the lower one.

I claim as new and desire to secure by Letters Pateuto 1. The employment or use of the,two mullers O K, placed one above the other in the pan B, and arranged in such amanner as to rotate in reverse or opposite directions, substantially as and for the purpose herein set forth.

2. The arrangement and combination of the central fixed conical hub, 0, at the center of the pan B, spindle E, tubular shaft D, eonieal hub J of muller K, and the hollowhub' Q of thriller 0, provided with arms R, fitted on the sleeve M, which is placed on the upper part of spindle E, with the screw N fitted in a it, substantially as and for the purpose de- H. BoLrnorF;

scribed. a requisite quantity of mercury, which be- Witnesses M. M. LIVINGSTON, 0. L. TOPLIFF. 

